More from the Guardian:
One cable said: "According to al-Husseini, the crux of the issue is twofold. First, it is possible that Saudi reserves are not as bountiful as sometimes described, and the timeline for their production not as unrestrained as Aramco and energy optimists would like to portray."
It went on: "In a presentation, Abdallah al-Saif, current Aramco senior vice-president for exploration, reported that Aramco has 716bn barrels of total reserves, of which 51% are recoverable, and that in 20 years Aramco will have 900bn barrels of reserves.
"Al-Husseini disagrees with this analysis, believing Aramco's reserves are overstated by as much as 300bn barrels. In his view once 50% of original proven reserves has been reached … a steady output in decline will ensue and no amount of effort will be able to stop it. He believes that what will result is a plateau in total output that will last approximately 15 years followed by decreasing output."
The US consul then told Washington: "While al-Husseini fundamentally contradicts the Aramco company line, he is no doomsday theorist. His pedigree, experience and outlook demand that his predictions be thoughtfully considered."
Seven months later, the US embassy in Riyadh went further in two more cables. "Our mission now questions how much the Saudis can now substantively influence the crude markets over the long term. Clearly they can drive prices up, but we question whether they any longer have the power to drive prices down for a prolonged period."
A fourth cable, in October 2009, claimed that escalating electricity demand by Saudi Arabia may further constrain Saudi oil exports. "Demand [for electricity] is expected to grow 10% a year over the next decade as a result of population and economic growth. As a result it will need to double its generation capacity to 68,000MW in 2018," it said.
It also reported major project delays and accidents as "evidence that the Saudi Aramco is having to run harder to stay in place – to replace the decline in existing production." While fears of premature "peak oil" and Saudi production problems had been expressed before, no US official has come close to saying this in public.